Chloe McCardel entered the water at 9:59 a.m. Havana time. She has been training for the past nine months to swim the approximately 100-miles across the Florida Straits without using a shark cage or wet suit.

The 28-year-old has already made six swims across the English Channel. The Cuba-to-Florida swim could take as long as 60 hours.

"I’ve swum the English Channel, and that’s like climbing Everest," McCardel said in a statement Tuesday. "But swimming from Cuba to the US is five times as far, and I hope to be the first to do this without the use of a shark cage or wet suit."

McCardel has a team of 50 specialists working around the clock to support her including boat captains, observers, navigators and divers to keep sharks away.

"We're employing some amazing ecologically sensitive shark repellent technology" McCardel said. "I'm confident that the provisions put in place by my team of scientists, as well as those watching the ocean currents will get me across."

Diana Nyad Ends Latest Cuba-to-Florida Swim Attempt

Diana Nyad swam a ceremonial final leg to shore in Key West Tuesday afternoon after ending her latest attempt to swim from Cuba to Florida earlier in the day. As soon as she walked onto the sand, a welcoming committee gathered on the beach sang "Happy Birthday" to Nyad, who turns 63 on Wednesday. She expressed a bit of disappointment about failing to make her complete, ambitious journey, but said she got a life lesson out of it.